alt process – Is taking photos with the back side of a film roll a real technique?

Yes, this technique is known as redscale. You can find a decent amount of information by googling using that term, and see example photos on Flickr. As @MichaelC notes in the comments, on 35mm you’d have to figure out a way of extracting the film from the canister, invert it, and put it back.

You can even do this on B&W film, and there will be an effect, since the light will now be passing through the anti-halation layer first.

I don’t want to waste an entire film roll and realise it didn’t work.

It will work, in the sense that you will get some results out of it, but as with any alternative technique, you pretty much have to be prepared to waste rolls of film (more than one) as you experiment. 🙂 Plus, things can go wrong when unloading and reloading the film into the cartridge.

On the other hand, Lomography makes a redscale film that you load in the normal way – perhaps worth a try as a first approximation to see if you like the results.